For best performance go for an Intel i7, LGA2011 3960X/3930K or LGA1155 3770K/2700-2600K.
LGA is the socket type and must match on the motherboard, the 3### is the model and are in roughly descending order.

Without a budget it is really hard to make any solid recommendations though.

with a 1300 hundred dollar budget i would consider the i7 3770k on a nice z77 board made by asus or asrock (asus sabertooth is pricey but apparently it's amazing), a radeon HD 7850 is the best bang for your buck, or a GTX 580 around the same price, those will run almost any game on high at a good frame rate. I wouldn't go for more than 8 GB ram unless you can get a good deal on a 12 GB or 16 GB, get a SSD for your boot drive and like 2 TB for your data drives. Look for combos on NewEgg and you can get that stuff for like 1000-1100 bucks and get yourself a nice monitor, mouse, case and keyboard =)

Pen tablet? I don't have one but I really want to use one for photoshop. A powered USB hub is a good bet.... and I would dare say you need a small mixer to control your audio properly. I'm a sound engineer though so haha!